Method of rolling sheet metal and apparatus therefor



April 6, 1943. E. A. NELSON METHOD OF ROLLING SHEET METAL AND APPARATUSiI-IEREFOR Filed April 26, 1941 3 Sheets-Sheet 1 Ya NMQ NW U H r n V F QQ NNI- WW 0 April 6, 1943. E. A. NELSON METHOD OF ROLLING SHEET METALAND APPARATUS THEREFOR Filed April 26, 1941 3 Sheets-Sheet 2 3Sheets-Sheet 3 E. A. NELSON Filed April 26, 1941 METHOD OF ROLLINGSHEET. METAL AND APPARATUS THEREFOR #3 I I} I April 6, 1943.

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(222 (222 WWW Patented Apr. 6, 1943 I UNITED STATES PATENT'OFFICE-2,315,810 METHOD or ROLLING snnar METAL AND ArrAnA'rUs 'rmmaron Emil A.Nelson, St. Clair Shores, Mich. Application April 26, 1941, Serial No.390,490 13 Claims. (01. 80-19) This invention relates to the rolling ofsheet metal and particularly to the rolling of metal sheets to providethem with varying cross-sectional configurations and has particularrelation to the rolling of metal sheets which taper in thickness over athereof.

Objects of the invention include the provision of a method of operatingupon a metal sheet to vary its transverse cross-sectional configurationat different points in the length thereof; the provision of a method ofrolling metal sheets to vary the thickness thereof at diflerent pointsin the length of th sheet; the provision of a method of rolling metalsheets to tapered or other conformation comprising passing a sheetbetween a pair of cylindrical rolls having a constant center distanceand in contact with a mandrel varying in cross-sectional configurationin a manner complementary to the variations desired in the final sheet;the provision of a method of rolling metal sheets a above described inwhich the advanced edge of the sheet passing through the roll is placedunder a pull or tension tending to advance the sheet at a faster rate oftravel than the peripheral speed of the rolls; the provision of a methodof rolling metal sheets as above described in which both the mandrel andthe sheet are placed under a pull or tension tending to advance themthrough the rolls; the provision of a method as above described in whichthe pulling force applied to the mandrel is different from the pullingforce applied to the sheet; and the provision of a method as abovedescribed in which a pulling force is applied to the sheet and mandrelbeing passed through the rolls and a retarding force is applied to thesheet and mandrel on the entrance side of the rolls.

Other objects of the invention include the provision of apparatus forrolling metal sheets to varying cross-sectional configurations; theprovision of means for rolling metal sheets to varying cross-sectionalconfigurations including a pair of cylindrical rolls arranged in spacedrelation and with their ax'es held at a constant distance with respectto each other, a mandrel adapted to be passed through the rolls andhaving a cross-sectional configuration varying in complementary relationwith respect to the desires. varying cross-sectional configuration ofthe desired final product, together with means for applying a pull onthe forward end of a sheet associated with the mandrel and being passedthrough the rolls therewith, tending to advance the forward end of thesheet at a faster rate of portion or all of the length movement than theperipheral rate of movement of the rolls; the provision of apparatus asabove described in which means are also provided for exerting a pull onthe mandrel in its passage through the rolls; the provisionof"'apparatus as above described in which the means provided forexerting a pull on the sheet is movable with the means provided forexerting a pull on the mandrel; the provision of apparatus as abovedescribed in which the means for exerting a pull on the sheets includesreleasable jaw means for gripping the forward end of the sheet beingpassed through the rolls; the provision of apparatus as above describedin which the means for exertinga pull on the mandrel comprises a.reversibly movable belt-like element; the provision of apparatus of thetype above described in which the means for exerting a pull on theforward edge of the sheet comprises fluid operated means operativelyconnected to the belt and bodily movable therewith; and the provision ofapparatus as above described in which means are provided on the entranceside of the rolls for gripping the sheet and the mandrel to apply aretarding eiiect thereto during the passage of the sheet and the mandrelthrough the rolls.

The above being among the objects of the present invention the sameconsists'in certain novel features of construction, combinations ofparts, and step or steps of operation to be hereinafter described withreference to the accompanying drawings, and then claimed, having theabove and other objects in view.

In the accompanying drawings which illustrate a suitable embodiment ofapparatus constructed in accordance with the present invention and whichis suitable for use in carrying out the method of the present invention,and in which like numerals refer to like parts throughout the severaldifferent views,

Fig. l is a more or less diagrammatic, partially broken, sideelevational view of rolling apparatus constructed in accordance with thepresent invention;

Fig. 2 is a transverse the line 2-2 of Fig. 1;

Fig. 3 is an enlarged, fragmentary, vertical sectional view takenlongitudinally through the rolling apparatus shown in the previous viewsand illustrating the construction of the same in greater detail andshowing the positions which the various parts assume as a rollingoperation is about to be initiated;

Fig, 4 is an enlarged; fragmentary, horizontal sectional view takenthrough the rolling appasectional view taken on ratus shown in theprevious views in a plane passing between the rolls and above themandrel thereof;

Fig. 5 is a fragmentary view of a portion of the apparatus shown in Fig.3, in the same plane as Fig. 3, but on a larger scale and illustratingthe relation of certain parts thereof after the sheet has passed afurther distance through the rolls;

Fig. 6 is an enlarged, fragmentary, plan view showing a rolledsheetsupported on the mandrel employed in the apparatus shown in the previousv views;

Fig. 7 is a vertical sectional view taken on the line I-I of Fig. 6;

Fig. 8 is a vertical sectional view taken transversely of the mandreland sheet shown in Figs. 6 and 7 and taken as on the line 8-8 of Fig. 7;

Fig. 9 is a view similar to Fig. 6 but illustrating a modified form ofmandrel and resulting sheet;

Fig. 10 is a vertical sectional view taken transversely of the mandreland sheet shown in Fig. 9 as on the line III-l0 thereof;

Fig. 11 is a view similar to Figs. 6 and 9 but showing a still modifiedform of mandrel and sheet;

Fig. 12 is an enlarged fragmentary, vertical sectional view takenlongitudinally of the mandrel and sheet shown in Fig. 11 as on the linel2l2 thereof; and,

Fig. 13 is a vertical sectional view taken transversely of the mandreland sheet shown in Fig. 11 and taken as on the line |3-i3 thereof.

The desirability of producing sheets of metal of tapering thickness overthe whole or part of the length thereof, or otherwise having varyingcross-sectional configurations, has long been recognized and althoughmany attempts have been made to produce such sheets none of them havebeen commercially practical. The use of sheets of tapered conformationhas a possibility of wide application either in the form of sheets orfabricated into structural members for various uses. One of theprincipal possible fields at the present time is in connection with thefabrication of aircraft where sheets of tapered conformation maythemselves be employed as the covering for the wings and fuselage andsuch sheets may be fabricated into structural members such as spars orthe like for the wings or fuselage to automatically obtain the desiredvariation in required strength over the length thereof coupled withminimum weight and without the necessity of riveting together separateelements each of a different and constant thickness.

The present invention may be used for forming tapered or other sheetshaving a varying cross-sectional configuration from any desired metal.Where such sheets are to be employed in airplane construction they will,of course, ordinarily be formed of light metal such as aluminum ormagnesium and in such event the rolling operation may be performed whilethe metal is in a cold state. Where such sheets are to be formed fromsteel, for instance, they may if de-- sired or necessary be heated forthe purpose of the rolling operation. The apparatus shown in theaccompanying drawings has been designed primarily for rolling lightmetal sheets and, accordingly, 'no means for maintaining them in heatedcondition is illustrated since it is not necessary, but those skilled inthe art will readily understand how this may be accomplished wherenecessary or desired.

In accordance with the practices of the present invention the tapered orotherwise formed sheets are made from conventional rolled sheets ofconstant thickness throughout and these stock sheets may be operatedupon in a rolling mill of conventional construction and employingconventional rolls. Preferably the rolling mill is of a type in whichthe rolls can be securely locked in a predetermined spaced relationshipwith respect to each other and in a manner which will prevent springingof the rolls away from each other under the stress of the-rollingoperation. The rolls employed are conventional cylindrical rolls. Forthe purpose of ease and clarity of description it will hereinafter beassumed, unless otherwise specified, that the sheet to be produced is tohave a uniform taper from one end thereof to the opposite end thereof,in other words one end of the sheet will be thicker than the oppositeend of the sheet and the thickness will vary uniformly from one endthereof to the opposite end thereof.

In following out the practices of the present invention to form such atapered sheet from a stock sheet of uniform thickness and by means of arolling mill having cylindrical rolls, a memher is formed preferablyhaving a length greater than and a width equal to or greater than thewidth of the piece of stock to be worked upon. This member functions insome respects as a die, and in some respects as a platen but for thewant of a better term is referred to herein, both in the specificationand claims, as a mandrel." This mandrel may be made from a suitablethickness of hardenable steel plate one or both sides of which aremachined or otherwise worked upon to taper its thickness over its lengthin exact accordance with the variation of thickness desired in thelength of the finished sheet to be produced. The mandrel is preferablyhardened after machining and its surface preferably polished or groundto bring it to a suitable degree of finish. The rolls of the rollingmill are adjusted in parallel relation with respect to each other and sothat the space between them is equal to the thickness of the mandrelplus the desired thickness of the sheet to be produced at any point inthe length of the mandrel and sheet. The sheet selected as the piece ofstock is of equal thickness throughout and equal in thickness to andpreferably a few thousandths thicker than the thick end of the desiredtapered sheet to be rolled and this stock sheet is placed over or under,and preferably over, the mandrel, and the mandrel and the superposedsheet is positioned for entrance between the rolls of the mill with thethin end of the mandrel positioned to be introduced into the mill. blyof the mandrel and work sheet will, of course, vary in thicknessaccording to the variation in thickness of the mandrel itself. Assumingthe mill to be operating, the assembly comprising the mandrel and itssuperposed sheet is then inserted between the rolls and such assembly isthen fed through the rolls. As will be appreciated, inasmuch as therolls are positioned with a fixed center distance during the rollingoperation the thickness of the assembly of the mandrel and the sheet asit emerges from the rolls will be uniform from one end thereof to theopposite end thereof. Inasmuch as the mandrel is of a hardened nature noreduction in the thickness of the mandrel can result in passing throughthe rolls and consequently such reduction in thickness must occur in thework sheet itself, the

result being that the thickness of the work sheet The initial asseni- 3the other in. a complementary manner to the in carrying out the methodof the present invenvariation in thickness of the mandrel, thus protionand in the explanation of which the method vlding the desired finalproduct. of the present invention will be more clearly It may be foundnecessary in some cases. because of the nature of the metal being rolledor because of the amount of reduction desired in thickness between oneend of the final sheet and the other, that the tapering of the sheet beaccomplished in two or more stages. In other words it may be necessaryto first follow out the above described operations on a sheet of stockto thus taper it from one end to the other but with a less amount oftaper than is desired in the final product, and then take this partiallytapered sheet and pass it through one or more similar operations in eachof taper is increased. In such case, of course, a separate mandrel willbe required for each pass through the mill and each mandrel will have asuccessively greater taper than its predecessor, Sheets of light metaltapered to an extent requiring reduction of thickness equal to 70% atone end thereof have been produced in one operation by the practices ofthe present invention and, accordingly, where light metal is beingworked on it will be appreciated that seldom if ever will more than onepass through the rolls be required.

The steps of operation above described in the formation of a taperedsheet are, however, not sufficient in and of themselves, to be reliedupon in the commercial manufacture of such sheets. This is for thereason that if a fiat sheet of stock is simply placed on a mandrel andfed through the rolls as described, the thinner trailing end portion ofthe resulting tapered ,sheet will invariably be bent laterally in onedirection or the other, an effect commonly known in the art asfishtailing, instead of having substantially straight sides throughoutits length. Such fishtailing will either render the sheet unfit for useor else require such a large amount of trimming as to involve a scrapcost disproportionate to the advantages gained. I have found that inrolling a sheet over a mandrel as above described the material of thestock sheet is discharged from the rolls at a faster rate than themandrel progresses through the roll. This effect is probably produced byan extruding effect on the metal of the stock sheet. I have found thatin order to prevent the flshtailing of the sheet being rolled it isnecessary to exert a continuous and substantial pull on the sheet as itemerges between the rolls and that where such substantial pull isapplied to the sheet the fishtailing effect is eliminated and acommercial usable and satisfactory product results. The application of adrag to the sheet and the mandrel assembly as it passes into the rollsappears also to aid in the final product of a commercially usableproduct.

It also appears to be of material aid in producing a commerciallysatisfactory sheet in the manner described to also apply a pulling forceon the of which the degree brought out. The apparatus itself, however,involves certain novel features which in and of themselves form furtherfeatures of the invention.

Referring now to the accompanying drawings a conventional strip mill isindicated generally at A and as including a frame 20 between theopposite sides of which a pair of cylindrical rolls 22 are rotatablysupported in a conventional manner. The mill may, of course, be providedwith the usual screw downs (not shown) for controlling the spacing ofthe rolls 22 but in any event it is important that whatever means areemployed for locating the spacing of the rolls it be such as to enablethe rolls to be firmly locked in the desired spaced relation in such amanner 'as. to be substantially unyielding during/the passage of a pieceof work between them. The rolls 22 are geared or otherwise connectedtogether for equal rotational movement by means of gearing or themandrel but to a lesser extent than the pull on the tegral verticallyturned flange 44 like (not shown) contained within a housing 24 and maybe driven bymeans of a conventional electric motor 25.

As best illustrated in Fig. 3 a fixed table 26 is associated with themill A on the entrance side of the rolls 22 and a fixed table 26 isassociated with the mill on the discharge side thereof, the table 26extending into relatively close proximity to the rolls 22 while thetable 28 is outwardly spaced therefrom. The tables 26 and 26 areprovided with side rails 36 which project thereabove at each sidethereof and are transversely spaced from one another by a distanceslightly greater than the width of the mandrel which passes between themand which will hereinafter be more fully described. These side rails 30are for the purpose of guiding the mandrel straight into the rolls andto aid in maintaining its straight relation in its passage therethrough.The table 26 as best illustrated in Fig. 3 is preferably but notnecessarily provided with a covering 32 of suitable fabric or othermaterial which may serve to exert.

The table 28 is provided with depending side members 36 between which atopposite ends of the table 28 are rotatably supported a pair of rolls orthe like 38 encircling which is a belt 40. The belt 40 may be of anysuitable or desirable construction as, for instance, link chain, fabric,rubberized fabric, or a combination of such elements, but as a matter ofillustration only it is shown in the accompanying drawings as being of afabric or rubberized fabric construction. The rolls 38 are so positionedthat the top edges lie in parallel and substantially flush relationshipwith respect to the top surface of the table 26 and the belt 40 passesover the top of such table. The top of the belt 28 and the top of thecovering 32 for the table 26 lie in the same horizontal plane as theupper edge of the'lower roll 22 as indicated in Fig. 3.

Supported on the upper and at certain positions of its movement also bythe roller 34 is a slide member 42 having an inat its righthand end asviewed in Fig. 3. Fixed to the flange 44 for equal movement with theslide 42 is a cylinder unit 46 which also rests on the upper surface ofsurface of the belt to the belt 48 and in the particular constructionshown includes a pair of cylinders 48 arranged with their axes parallelto the path of movement of the slide 42 and the upper surface of thebelt 48. In the particular construction shown the belt 48 is fixed forequal movement to the slide 42 and the cylinder unit 46 by bringing thefree ends of the belt upwardly between the flange 44 and the opposed endof the cylinder unit 46 where they are firmly clamped between theseparts by means of bolts 68. The belt 48 is caused to move on the rolls88 by driving one of the rolls, the righthand roll 88 as viewed in Figs.1 and 3 being the driven roll in the particular construction shown. Inorder to drive it, its shaft 52, which is non-rotatably connected to it,is connected into a gear reduction unit 64, shown in Fig. 1, which inturn is driven by an electric motor 56. The electric motor 56 ispreferably either an induction motor or a direct current motor in orderthat it may exert a material amount of torque while turning considerablyunder its rated speed, this being for a purpose which will hereinafterbe more fully described.

Each cylinder 48 has a piston 68 therein which is mounted upon a pistonrod 62 projecting out of the righthand end of the cylinder as viewed inFigs. 3, 4 and 5 and such end of each cylinder is provided with asuitable packing gland 64 to prevent leakage of fluid therefrom aroundthe shaft 62. Connections 66 and 68 lead into the opposite ends of eachcylinder 48 for the purpose of introducing fluid and preferably a liquidunder pressure into either end of the cylinder and exhausting it fromthe opposite end thereof.

The projecting ends of the piston rods 62 are connected to a cross-bar18 as best illustrated in Figs. 3, 4 and 5 and at its opposite ends thecrossbar 18 is pivotally connected to a pair of links 12 which extend tothe left as viewed in the figures mentioned on opposite sides of thecylinder unit 46. The extreme outer ends of the ross-bar 18 are receivedin grooves I4 formed in the inner faces of the side rails 38 adjacentthe table 28, such grooves thus forming means for guiding the ends ofthe bar 18 during movement thereof longitudinally of the table 28. Asalso best brought out in Figs. 3, 4 and 5 the forward ends of the link12 are pivotally connected to a cylindrical bar or shaft I6 the oppositeends of which are also guided in the grooves 14 and which bar is alsoreceived in transversely spaced bosses 18 formed at the rear edge of aslide 88 which rests upon the upper surface of the slide member 42.Adjacent to but slightly spaced from the lefthand end of the slide 88,the slide 88 .is provided with a plurality of transversely spaced bosses82 extending through which is a second cylindrical rod or shaft 84. Theends of the shaft 84 are also received in the grooves 14 for guidingmovement therein.

Overlying the slide 88 is a clamping plate 86 which is preferably of thesame width as the sheet to be rolled. The forward or lefthand end of theclamping plate 86 is aligned with the lefthand end of the slide 88, andin line, with the various bosses 82 it is provided with complementarybosses fitting therebetween and rotatably surrounding the shaft 84 sothat the clamping plate 86 as a whole is pivotal about the axis of theshaft 84. The clamping plate 86 is normally disposed at an angle withrespect to the plane of the slide 88 but its forwardly projecting orlefthand end as viewed in the drawings is provided with a serrated orknurled lower face which when a work sheet is interposed between it andthe opposed face of the slide 88 lies in substantially parallelrelationship with respect to the upper face of the slide 88. Thatportion of the upper face of the slide 88 opposed to the serrated orknurled lower face of the clamping plate 86 is likewise serrated orknurled.

The rear or right end edge of the clamping plate 86 is notched out, asat 88, at transversely spaced points, shown as two in the particularembodiment of the apparatus shown, and received in these notches 88 andpivoted to the clamping plate 86 therein by means of a transverselyextending shaft 88 is the upper end of a cylinder member 82. A pistonmember 84 rec-lprocably received in each cylinder 82 is arranged withits lower end pivotally mounted on the shaft I6 which also serves toconnect the links 12 to the slide 88 as previously described. Eachcylinder 82 is provided with a connection 86 leading into it above itspiston 84 and such connection is connected by a flexible tube 88 to asuitable source (not shown) of fluid, and preferably liquid, underpressure. As will be appreciated, when fluid under pressure isintroduced through the tube 88 and connection 86 into the interior ofthe cylinders 82 it will tend to project the pistons 84 from theircorresponding cylinders 82 and cause the clamping plate 86 to pivot in acounterclockwise direction of rotation as viewed in Figs. 3 and 5,bringing the forward or clamping edge of the clamping plate 86downwardly with respect to the forward edge of the slide 88. One or moresprings 88 are tensioned between the clamping plate 86 and the slide 88and constantly urge the clamping plate 86 toward a clockwise directionof rotation as viewed in Figs. 3 and 5, thereby tending to draw theforward clamping end of the clamping plate 86 away from the opposedsurface of the slide 88.

As previously mentioned it is assumed, for the purpose of illustrationin the particular embodiment of the apparatus shown, that it is desiredto form a sheet of light metal such as aluminum of uniformly taperedcharacter from one end thereof to the other and to accomplish this amandrel I88 is employed. As perhaps best brought out in Figs. 6, '7 and8 the mandrel I88 is preferably wider than the sheet which is to beoperated on and where employed with apparatus of the specific charactershown and described is preferably of such width as to be relativelyclosely but readily slidable between the side bars 88. While the averagethickness of a mandrel to be used may vary considerably in differentjobs, the mandrel should be sufficiently thick to enable it to behandled and passed through the mill without bending or distortion. Thismandrel I88 shown tapers in thickness from one end toward the other endthereof by an amount exactly equal to the taper desired in the finishedtapered sheet. In other words, if for example the finish tapered sheetis to taper uniformly in thickness an amount equal to five thousandthsof an inch per foot of length, then the main body portion of the mandrelis correspondingly tapered. The mandrel is, of course, preferably madefrom a hard enable steel suitably hardened and with that surface thereofwhich is -to receive the sheet suitably ground and polished to insure anequivalent flnish on the sheet to be produced. The mandrel may, ofcourse, be and preferably is of greater length than the finished sheet.

Any suitable means may be provided for connecting the forward oradvanced end of the mandrel, shown as the righthand end in Figs. 3, 4

V and 5, for instance, to the slide 42 but preferthat the advanced endof the mandrel I which is thus notched is reduced in thickness toapproximately the same thickness as the slide 42,

this being for the purpose of permitting the slide 80 to move to theleft when moving to loading po sition as illustrated in Fig. 3 to bringits forward or lefthand end as viewed in Fig. 3 over the notched outportion of the mandrel. It will be appreciated that the mandrel I00 andslide member 42 may be disconnected from one another when the mandrelI00 is passed completely through the rolls 22 by simply lifting itupward ly and then away from the slide member 42.

Additionally, and as best brought out in Fig. 3, the forward orrighthand end of the mandrel I00 is preferably reduced in thickness overa length such as indicated at H6 so that such forward end of the mandrelI00 and the sheet H8 superposed thereon may be introduced between therolls 22 and the sheet clamped to the slide 80 before the rolls 22 willgrip the mandrel and sheet between them. It will be understood that theend of the mandrel which is notched out at H0 and reduced in thicknessover the length I I6 is the thin end of the mandrel for reasons whichwill hereinafter be apparent.

0n the entrance side of the rolls 22 or to the left thereof as viewed inFig. 3 a bar I20 is extended between the opposite sides of the frame 20and pivotally connected to the bar'by means of pivot pins I22 are aplurality, shown as two, cylinders I24. Each cylinder I24 reciprocablyreceives therein a piston I26. The pistons I26 are in turn pivotallyconnected by means of pins I28 to a presser bar I30 which is preferablyprovided with a fabric or other frictional covering I32 fixed theretoand extending over the lower face thereof. The presser bar I30 isadapted to a press downwardly upon the upper surface of the sheet I I8and act therethrough to force the mandrel I00 down into contact with thefrictional surface 32 of the table 26, thereby to set up a frictionaldrag tending to resist movement of the mandrel I 00 and sheet II8through the rolls 22. Fluid and preferably liquid under pressure isintroduced into the cylinders I24 through a suitable line I34 connectedto a suitable source of pressure and preferably one or more springs I36see Fig. 2) cooperating between the presser foot I30 and the bar I20constantly tend to raise the presser foot I30. Thus when pressure in thecylinders I24 is relieved the springs I36 will raise the presser footI30, and when pressure is applied to the cylinders I24 such pressureacting on the pistons I26 will force the presser foot I30 downwardlyagainst the force of such springs and into operative engagement with thesurface of a sheet II8 passing therebelow.

In the operation of the apparatus thus described it is, of course,assumed that the mandrel I00 has been connected to the slide 42 byinterengagement of the dovetailed edges thereof and that the motor 56has been reversed so as to move the slide 42 to its extreme position ofmovement to the left and as viewed'in Fig. 3. Fluid under Pressure hasbeen introduced into'the cylinders 48 through the connections .58 5ndthe fluid at the opposite ends of the cylinders has been allowed toescape through the connection 66 so as to move the pistons 60 andconsequently the slide to its extreme position of movement to the leftas shown in Fig. 3. Pressure in the cylinders 92 and I24 has beenrelieved so that the cooperating springs I00 and I36, respectively, havelifted the forward or lefthand end of the clamping plate 86 and haslifted the presser foot I30. A sheet I I8 of the desired material to beworked upon and of the required width and length is then placed upon themandrel I00 and its forward or righthand end as Viewed in Figs. 3, 4 and5 is passed under the presser foot I30 and under the upper roll 22 untilits forward or righthand edge passes under the clamping end of theclamping plate 86 and abuts against the hinge bosses thereof. Aspreviously mentioned the sheet H8 is of a width preferably slightlywider than that desired in the final tapered sheet and of-a length whichexperionce has shown will provide a final sheet of the desired length,plus an additional amount which overlies the reduced portion 6 of themandrel I00. This last portion is, of course, provided as an expedientin securing the sheet II8 to the slide 80, is not affected by therolling operation and will be removed in trimming the rolled sheet toits final dimension. The sheet I I8 is also preferably slightly greaterin thickness than the maximum thickness desired in the final taperedsheet. If the rolls 22 are rotating at this time no clamping action onthe sheet and mandrel between the rolls or movement of the sheet andmandrel will result because of the cut-away portion II6 of the mandrelI00 provided for preventing such clamping action.

The above operations having been accomplished, fluid under pressure isthen introduced into the cylinders 92 and I24 with the result that theclamping plate 86 is caused to pivot in a counter-clockwise directionand to clamp the forward edge of the sheet II8 between it and thelefthand end of the slide 80, and also causing the presser foot I 30 topress that portion of the sheet II8 thereunder firmly down into contactwith the upper surface of the mandrel I00 and firmly press the mandrelI00 downwardly into contact with the covering 32 for the table 26.

If the rolls 22 are power driven and not already rotating, they are thenput in operation, and the motor 56 is energized to cause the righthandroll 38 to turn in a clockwise direction of rotation as viewed in Figs.3 and 5. Rotation of the roll 38 in the direction described causes theupper side of the belt 40 to move to the right as viewed in Figs. 3 and5 carrying with it the slide 42, cylinder unit 46 and all of the partsinterconnected therewith including the mandrel I00 and the sheet II8.Initial movement of the mandrel I 00 and sheet II8 to the right asviewed in Fig. 3 will and sheet II8 into gripped relation between therolls 22, and as soon as this occurs fluid under pressure is introducedinto the lefthand end of the cylinders 48 and permitted to exhaust fromthe righthand end thereof. Once the mandrel I00 and sheet H8 is grippedbetween the rolls 22 it will, of course, be appreciated that no ordinaryforce exerted by either the belt 40 or the cylinders 48 will be capableof advancing the mandrel and the sheet through the rolls at a bring themandrel I00 rate faster than the rotation of the rolls 22 permits. Inother words such forces will not be able to slide the mandrel I andsheet H8 through the rolls faster than the rolls rotate. On the otherhand in order to be effective it will be appreciated that the pull onthe belt 40 must exceed the pull exerted by the pistons 80 in thecylinders 48. Preferably the pull exerted by the belt 40 is roughlytwice the pull capable of being exerted by the pistons 80.

Assuming the various operations and conditions above explained to beexisting and the mandrel I00 and sheet H8 having been advanced intogripping relationship with respect to the rotating rolls 22, the mandrelI00 and sheet H8 will be drawn through the rolls 22 as well as beingforced therethrough by the friction thereof with the rolls where therolls are driven, overcoming the resistance of the presser foot I30, andwill continue to pass through the rolls 22 until the sheet H8 has beenacted upon over its length rearwardly or to the left of the cut-awayportion H6 of the mandrel I00. Inasmuch as the rolls 22 are arrangedwith fixed axes and are of an unyielding nature the assembly of themandrel I00 and sheet H8 in the condition which it finally emerges fromthe rolls 22 will be of uniform thickness from the reduced portion H6 ofthe mandrel I00 rearwardly or to the left. The mandrel I00 being of anunyieldable nature the material of the sheet H8 is the only element ofthe combination that may yield and, accordingly, in passing through therollers 22 its thickness is necessarily reduced in an amountcomplementary to the taper of the mandrel. Thus the sheet H8 as it comesfrom the rolling process is tapered in thickness from one end thereof tothe opposite end thereof excepting only that portion of the sheet whichoverlies the portion H8 of the mandrel I00 and which portion in thefinal product will ordinarily be removed as scrap.

During the rolling operation above described it will be appreciated thatnot only is the mandrel I00 being pulled in the direction of itsmovement through the rolls 22 but the sheet H8 is also being pulled inthe direction of its movement through the rolls 22 and in a manner moreor less independently of the mandrel and so that the advanced end of thesheet H8 may be moved at a different rate of speed than the mandrel I00.I have found that this feature is essential in order to preventfishtailing of the sheet being rolled and is necessary for the followingreasons. I have found that in rolling a sheet such as H8 upon a mandrelI00 the sheet H8 appears to extrude forwardly or in the direction ofmovement of the sheet through the rolls so that the end of the sheetwhich has passed through the rolls moves at a greater speed than theperipheral speed of the rolls.

The amount which the sheet H8 thus advances with respect to theperipheral speed of the rolls and the linear speed of the mandrel I00will, of course, vary with the amount of reduction to which the sheet H8is being subjected and to the material from which it is formed. Asillustrative of this movement which occurs it may be stated thatexperiments have shown that a sheet such as H8 formed of aluminum andapproximately six feet in length and tapering in thickness from 0.064"at one end to 0.020" at its opposite end will be projected from therolls 22 at a faster rate than the peripheral speed of the rolls event Ihave found that it is necessary in order to prevent flshtailing of thefinal product to keep the sheet H8 on the discharge side of the rollunder a constant and material tension and at the same time it ispreferable to retard the passage of the sheet and the mandrel into therolls as by means of a presser foot such as I or other equivalent means.This tension on the sheet H8 as it passes through the rolls is, ofcourse, obtained by means of fluid pressure in the cylinders 48 actingon the pistons 80, the pistons 80 and parts connecting them to theadvanced edge of the sheet H8 moving to the right as viewed in thedrawings, with respect to the belt 40, slide member 42 and mandrel I00,until near the end of the operation these parts may have assumed therelative positions indi cated in Fig. 5. In connection with the passageof the sheet H8 through the rolls 22 it may be stated that experimentsindicate that it is preferable, particularly where the amount ofreduction of the sheet H8 is relatively great, that its passage throughthe rolls 22 be relatively slow, for instance at a rate of 24 to 48 feetper minute, so that the metal being displaced in the sheet II 8 by therolls may have ample time to fiow. Sheets thus rolled at the speedsindicated appear to be superior to sheets rolled at higher speeds,although it is to be understood that higher speeds may unquestionably beutilized particularly where the amount of reduction of the sheet at itsthin end is less than the particular instance cited. It will also beappreciated that in the particular instance cited the thin end of thecompleted sheet. has been reduced approximately 70% in thickness ascompared to its original thickness, this large amount of reduction inthe thickness being approximately three times as great as it is possibleto successfully obtain in the commercial rolling of fiat sheets inaccordance with present day practices.

The sheet H8 thus having been rolled as above described and having beenpassed through the rolls 22, the feed of fluid under pressure to thelefthand end of the pistons 80 is stopped and the motor 58 isde-energized so as to stop the belt 40. The fluid pressure in thecylinders 92 and I24 is thereupon relieved permitting the springs I00and I88 to release the clamping plate 86 from the sheet H8 and to raisethe presser foot I30, and the sheet H8 is then removed. The motor 56 isthen reversed so as to move the slide 42 and the mandrel I00 to the lefttotheir initial loading positions and fluid under pressure is admittedto the righthand side of the piston 60 and allowed to escape from thelefthand end of the cylinders 48 so as to permit the slide 80 to returnto'its loading position, after which another blank sheet H8 maybeinserted into place and the sequence of operations described andrepeated.

One thing may be noted in connection with the pull exerted by thecylinders 48 and the pistons 80 on the sheet being rolled and that iswhere a relatively narrow sheet is being rolled and brought torelatively thin condition at one end thereof it may be desirable toreduce the fluid pressure on the pistons 80 as the thickness of thesheet H is reduced by the rolls 22 so as not to endanger pulling thesheet apart. While this may be accomplished in any suitable manner,either automatically or manually, one method of accomplishing thismanually is illustrated in Fig. 3 in which it will be noted that thesupply line 66 is provided with amanually operable control valve I50 anda pressure gauge I52 is interposed between the valve I50 and the forwardend of the cylinders 48. Particularly where the mandrel and sheet arefed through the rolls at the slow rate above indicated as preferable, anoperator may manually operate the valve I50 to gradually reduce thepressure being applied to the piston 60 as the sheet II8 progressesthrough the rolls 22. The condition desired, of course, is to maintain asubstantially constant tensile stress on the sheet H8.

It should be appreciated by those skilled in the art that the mountingof the cylinder assembly 46 on the belt 40 could be dispensed with in sFor instance, in Figs. 0 and 10 the sheet 200 there shown may beprovided with a thick end 202 and a thin end 204. It is of greater widthat its thick end than at its thin end. Additionally, it is provided onits under surface with a plurality, illustrated as three, generallylongitudinally extending ribs 206 which ribs may converge slightlytoward one another towards the thin end of the sheet as illustrated. Theribs themselves may practicing the method of the'present invention andthe cylinder assembly 46 be independently and fixedly mounted andconnected in the manner shown or otherwise with the advanced end of thesheet II8. Under such circumstances the belt 40, its driving means andconnection to the mandrel I00 might be dispensed with entirely where therolls 22 are driven, the friction be tween the lower roll 22 and themandrel being relied upon to pass the mandrel through the rolls'withoutany pulling force being applied thereto. The only disadvantage of suchmodified construction would be that the cylinder assembly 46 would berequired to be of a length in excess of the length of the sheet II8being rolled, whereas in the particular apparatus illustrated the lengthof the cylinder assembly 46 need only be slightly greater than theamount which the sheet II8 advances from the rolls in excess of theperipheral travel of the rolls. Consequently with the construction shownthe cylinder assembly 46 is of minimum length, is relatively inexpensiveto build or purchase and, having a short stroke, may be readily andquickly operated particularly when returning it to its loading position.It will also be appreciated by those skilled in the art that from thestandpoint of the broad method of the present invention the use of thebelts 40 to move the mandrel I00 is merely one expediency and thatmovement of the mandrel I00 may be accomplished in a suitable ordesirable manner either independently of or simultaneously with themeans for applying a tension on the sheet II8.

From the above it will be appreciated that if instead of desiring afinished sheet of uniform taper from one end thereof to the opposite endthereof a sheet having different degrees of taper, or only one ordifi'erent portions of the length thereof tapered, all that is necessaryto do is to form a mandrel whose thickness tapers or varies in acomplementary manner to that of the desired final sheet and aftersuperimposing a sheet of material of uniform thickness over the mandreland of amaximum thickness equal to or preferably slightly greater thanthe maximum thickness in the desired final sheet, pass the same throughthe rolls in the same manner as described in connection with the sheet II8 to obtain the desired final product. It is also possible to form ribseither longitudinally or transversely of such sheet or depressions orpockets in such sheets in addition to the taper applied thereto byfollowing out the same general practices.

sheet 200 will, of course, be of substantially less length than thefinished sheet 200 under the cir-.

cumstances assumed, it will be tapered in width and have a wide endequal to the wide end 202 of the finished sheet 200 or" of slightlygreater width and a narrow end of substantially the same or slightlygreater width than the narrow end 204 of the sheet 200. In thickness itwill preferably be equal to the combined thickness of the sheet 200 andthe ribs 206 at the thick end of the finished sheet. Obviously as suchsheets and mandrel are passed through the rolls 202 described orequivalent rolls and otherwise acted upon in the manner described, it'will be transformed into the desired final sheet 200.

On the other hand a tapered sheet such as the sheet 220 illustrated inFigs. 11, 12 and 13 having transversely extending ribs 222 on its lowersurface may be desired. In such case the cooperating mandrel 224 will betapered in thickness over its length or a portion of its length inaccordance with the desired taper or variation in thickness in thedesired final sheet and its upper surface will be provided withtransversely extending grooves 226 complementary to the desired ribs 222to be formed in the sheet 220. The blank sheet or work sheet which willbe employed in such case will preferably have a thickness equal to themaximum thickness of the sheet 220 and ribs 222 at the thick end of thesheet and in passing the mandrel 224 and blank sheet received thereonthrough the rolls it will be formed to the desired final shape andthickness in the same general manner as in the preceding cases as willbe appreciated.

One thing may be noted, however, in the practices of the presentinvention and which will be of aid from a commercial standpoint, andthat is that because of the difficulty liable to be experienced inconnection with the rolling mill employed in connection with theinvention in adjusting the rolls to bring them to the desired spacingand parallelism, it is preferable in designing different mandrels foruse in rolling sheets of various sizes, thicknesses, tapers or otherwiseon a single mill to so construct the mandrels that all of them withtheir superposed sheets may be passed through the rolls withoutnecessitating adjustment of the position of the rolls. In other wordswhen designing mandrels to roll various tapered or other sheets varyingin some respects from one another it will be found to be of great aid toso design them that the combined final mandrel and sheet thickness ofall of them are identical, as in such case one mandrel may besubstituted for another one in the mill but without requiring adjustmentof the rolls of the mill and subsequent checking and re-adjustment ofthe rolls to bring them to the desired spacing and parallelism. Undersuch conditions it will be found that a number of sheets each havingdifferent characteristics may be relatively rapidly rolled' one afterthe other or in multiples simply by changing mandrels in each instance.

From the above it will be appreciated that the present inventionprovides a method by means of which sheets of metal which vary inthickness from one end thereof to the other end thereof or over aportion of the length thereof may be quickly and accurately producedfrom ordinary stock sheets of uniform thickness. It will also beappreciated that apparatus to carry out such method may be embodied in anumber of different mechanisms of varying types and construction, theparticudar apparatus shown by way of illustration constituting apreferred apparatus for use in carrying out the method and itselfinvolving certain features constituting a more specific part of thepresent invention.

Having thus described my invention which I claim by Letters Patent is:

What I claim is:

1. In the manufacture of metal sheets differing in thickness and/orcontour at different points in the length thereof, the steps of forminga plate-like mandrel of a length and width at least as great as thelength and width of the desired final product and varying in thicknessand/or cross-sectional configuration at different points in the lengththereof in a manner complementary to the variation desired in the finalproduct, placing a sheet of the desired metal and of uniform thicknessthroughout in contact with a surface of said mandrel to form anassembly, passing said assembly through power driven rolls maintained ata fixed axial distance with respect to each other and spaced from eachother by a distance less than the maximum thickness of said assembly,and constantly maintaining that portion of said sheet discharged fromsaid rolls under a sufiicient longitudinal tension during passage ofsaid sheet through said rolls to move the leading edge of said sheet ata greater speed than said mandrel.

2. In the manufacture of metallic sheets having different thicknessesand/or cross-sectional configurations at different points in the lengththereof, the steps of forming a plate-like mandrel of at least the widthand length of the desired final sheet and varying in thickness and/orcross-sectional configuration at different points in the length thereofin a manner complementary to that desired in the final sheet, applying asheet of metal of constant thickness throughout against one surface ofsaid mandrel to provide an assembly, passing said assembly throughcylindrical power driven rolls having their axes fixed with respect toeach other and with the rolls spaced from each other by a distance lessthan the maximum thickness of said assembly, continually applying aforce to said mandrel during its passage through the rolls tending toadvance it therethrough, and continuously applying a pulling force tothe advanced edge of said sheet during its passage through said rollstending to advance it at a greater speed than said mandrel.

3. In the manufacture of metallic sheets having different thicknessesand/or cross-sectional configurations at different points in the lengththereof, the steps of forming a plate-like manassembly, applying a forceto said mandrel in addition to the force applied thereto by said rollstending to advance it through said rolls, and applying a force to theadvanced end of said sheet, in addition to the force applied to saidsheet by said rolls, tending to pull said sheet through said rolls inadvance of said mandrel.

31. In the manufacture of a sheet of metal tapered in thickness in thedirection of its length, the steps of forming a mandrel of a length andwidth corresponding to that portion of said sheet which is to be taperedand tapered in thickness in a manner complementary to the desired taperin said sheet, placing a sheet of metal of uniform thickness throughoutagainst a face of said mandrel to form an assembly, and then passingsaid assembly between cylindrical rolls fixedly spaced with respect toeach other by a distance less than the maximum thickness of saidassembly, constantly maintaining that portion of said sheet which haspassed through said roll under a material tension during the passage ofsaid sheet through said rolls whereby to advance it at a 9 eater speedthan said mandrel, and exerting a pull on said assembly during itspassage through said rolls tending to retard its passage through saidrolls.

5. In the manufacture of a sheet of metal tapered in thickness in thedirection of its length, the steps of forming a mandrel of a length andwidth corresponding to that portion of said sheet which is to be taperedand tapered in thickness in a manner complementary to the desired taperin said sheet, placing a sheet of metal of uniform thickness throughoutagainst a face of said mandrel to form an assembly, and then passingsaid assembly between cylindrical rolls fixedly spaced with respect toeach other by a distance less than the maximum thickness of saidassembly, applying a force to said mandrel during its passage throughsaid rolls tending to pull it through said rolls in advance of saidmandrel, separately applying a force to said sheet during its passagethrough said rolls tending to pull said sheet through said rolls, andexerting a pull-0n said assembly during its passage through said rollstending to retard its passage through said rolls.

6. Rolling apparatus comprising, in combination, a rolling millincluding a pair of spaced cylindrical rolls rotatably mounted thereinin a fixed, spaced relation with respect to each other, a plate-likemandrel of different thickness at different points in the length thereofadapted to receive a sheet of metal thereon and to be passed with saidsheet of metal between said rolls, and means on the discharge side ofsaid mill cooperable with a sheet being passed through said mill withsaid mandrel for placing that portion of saidsheet between its advancedend and that portion thereof gripped between said rolls and said mandrelunder a material tension.

'7. Sheet rolling apparatus comprising, in combination, a pair ofcylindrical rolls, means for rotatably supporting said rolls in spacedrelation and with their axes at a fixed distance with respect to eachother, a plate-like mandrel adapted to receive thereon a sheet of metaland adapted to be passed with said sheet thereon between said rolls,means for applying a pull to said mandrel during its passage throughsaid rolls tending to move it at a greater speed than the peripheralspeed of said rolls, and means for applying a pull to said sheet duringits passage through said rolls tending to advance said sheet throughsaid rolls at a greater speed than the peripheral speed of said rollsand the linear speed of said mandrel.

8. Rolling apparatus comprising, in combination, a rolling millincluding a pair of rotatable cylindrical rolls arranged in spacedrelation and at a fixed distance between the axes'thereof, a plate-likemandrel having different thicknesses at diflerent points in its lengthadapted to receive thereon a sheet of metal to be rolled and to bepassed therewith through said rolls, means on the discharge side of saidmill cooperable with said mandrel during passage thereof between saidrolls for applying a pull on said mandrel, and additional meansassociated with the last mentioned means inter-engageable with theadvanced end of said sheet for applying a pull to said advanced end ofsaid sheet during the passage of said sheet through said rolls tendingto move said advanced end at a faster rate of speed thansaid mandrel.

9. Apparatus for rolling metal sheets comprising, in combination, arolling mill including a pair of rotatable cylindrical rolls arranged inspaced relation, a plate-like mandrel and adapted to be passed betweensaid rolls and to support a work sheet against one face thereof duringsaid passage, means on the discharge side of said mill and movable inthe direction of movement of said mandrel therethrough connectible .tosaid mandrel to exert a pull thereon during its passage between saidrolls, and means in addition to the last mentioned means connectiblewith said sheet during its passage beteween said rolls operable to applya pull to said sheet during its passage between said rolls to advancethe forward end of said sheet at a different rate of speed than saidmandrel.

10. Apparatus for rolling metal sheets comprising, in combination, arolling mill including a pair of rotatable cylindrical rolls arranged inspaced relation and fixed against bodily movement with respect to eachother, a plate-like mandrel adapted to be passed beteween said rolls andto support a sheet against one face thereof during said passage, meanson the discharge side of said mill and movable in the direction ofmovement of said mandrel therethrough connectible to said mandrel toexert a pull thereon during its passage between said rolls, and means onthe entrance side of said rolls tending to retard the movement of saidmandrel and sheet into said rolls.

11. Apparatus for rolling metal comprising, in combination, a pair ofcylindrical rolls, means rotatably supporting said rolls in spacedrelation and at a fixed axial distance with respect to each of saidmandrel and sheet therethrough connectible with said mandrel, means formoving the last mentioned means, additional means on the discharge sideof the roll connectible with the advanced edge of said sheet during itspassage between said rolls, and additional means for applying a force tothe last mentioned means tending to move it in the direction of saidsheet through said rolls to maintain the said sheet under tension duringits passage through said rolls.

12. Rolling apparatus comprising, in combination, means rotatablysupporting a pair of cylindrical rolls in spaced relation with respectto each other, a plate-like mandrel of different thickness at differentpoints in its length adapted for passage between said rolls and adaptedto support a work sheet thereon during said passage, belt-like means onthe discharge side of said roll arranged with one surface thereofmovable in the direction of movement of said mandrel and sheet throughsaid rolls, means for connecting said belt-like means to said mandrel,means for driving said belt-like means whereby to exert a pull on saidmandrel during its passage through said roll, a pulling device securedto said belt-like means for equal movement therewith, and means forconnecting said pulling device to the advanced edge of said sheet.

13. Rolling apparatus comprising, in combination, means rotatablysupporting a pair of cylindrical rolls in spaced relation with respectto each other, a plate-like mandrel of difierent thickness at differentpoints in its length adapted for passage between said rolls and adaptedto support a work sheet thereon during said passage, belt-like means onthe discharge side of said roll arranged with one surface thereofmovable in the direction of movement of said mandrel and sheet throughsaid rolls,-means for connecting said beltlike means to said mandrel,means for driving said belt-like means whereby to exert a pull on saidmandrel during its passage through said roll, hydraulically actuatedpulling means secured to said belt-like means for equal movementtherewith and including a part movable relative thereto in the directionof movement of said belt-like means, and means for securing said part tothe advanced end of said sheet whereby to apply a pulling force to theadvanced end of said sheet during the passage of said sheet between saidrolls to advance said end at a faster rate than said mandrel is advancedthrough said rolls.

EMIL NELSON.

